Ultrasonication-assisted liquid-phase exfoliation enhances photoelectrochemical performance in α-Fe2O3/MoS2 photoanode

• Published in: Ultrasonics sonochemistry 2021-04, Vol.72, p.105403-105403, Article 105403
• Main Authors: Masoumi, Zohreh, Tayebi, Meysam, Lee, Byeong-Kyu
• Format: Article
• Language: English
• Subjects: 2D material; Original; Sonochemistry; Transition-metal dichalcogenides (TMD); Ultrasonic; Ultrasonication-assisted synthesis; α-Fe2O3/MoS2
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2020.105403

[Display omitted] •Ultrasonication-assisted synthesis of MoS2 nanosheets improved PEC performance.•Liquid phase exfoliation was used for MoS2 nanosheets with 6 nm thickness.•Photocurrent of α-Fe2O3 photoanode significantly increased by MoS2 heterojunction.•α-Fe2O3/8-MoS2 showed a thinner space charge layer and reduced flat band potential.•p-n junction decreased resistance due to the reduced recombination rate of charge carriers. This study successfully manufactured a p-n heterojunction hematite (α-Fe2O3) structure with molybdenum disulfide (MoS2) to address the electron–hole transfer problems of conventional hematite to enhance photoelectrochemical (PEC) performance. The two-dimensional MoS2 nanosheets were prepared through ultrasonication-assisted liquid-phase exfoliation, after which the concentration, number of layers, and thickness parameters of the MoS2 nanosheets were respectively estimated by UV–vis, HRTEM and AFM analysis to be 0.37 mg/ml, 10–12 layers and around 6 nm. The effect of heterojunction α-Fe2O3/MoS2 and the role of the ultrasonication process were investigated by the optimized concentration of MoS2 in the forms of bulk and nanosheet on the surface of the α-Fe2O3 electrode while measuring the PEC performance. The best photocurrent density of the α-Fe2O3/MoS2 photoanode was obtained at 1.52 and 0.86 mA.cm−2 with good stability at 0.6 V vs. Ag/AgCl under 100 mW/cm2 (AM 1.5) illumination from the back- and front-sides of α-Fe2O3/MoS2; these values are 13.82 and 7.85-times higher than those of pure α-Fe2O3, respectively. The results of electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis showed increased donor concentration (2.6-fold) and decreased flat band potential (by 20%). Moreover, the results of IPCE, ABPE, and OCP analyses also supported the enhanced PEC performance of α-Fe2O3/MoS2 through the formation of a p–n heterojunction, leading to a facile electron–hole transfer.